The proposed pilot study is an experimental design intended to investigate the preliminary efficacy of Interpersonal Social Rhythm Therapy for Bipolar II Depression (IPSRT-BPII). A total of 56 eligible subjects with a diagnosis of bipolar II disorder will be randomly assigned to one of two treatment groups : Seroquel (n=28) or IPSRT-BPII (n=28). Following baseline assessment, all participants will undergo up to 20 weeks of their assigned treatment. Patients assigned to IPSRT-BPII who fail to respond (at least 50% reduction in HRSD-25 scores and YMRS ≤ 10) by week 12 will have Seroquel added to IPSRT-BPII. Subjects who achieve remission (defined as 3 consecutive weeks where both HRSD-25 and YMRS scores average ≤ 7) and have participated in the trial for a minimum of 12 weeks will be moved into a continuation phase where they will receive maintenance treatment (bi-monthly therapy sessions and/or pharmacotherapy) until week 20. Patients who do not achieve remission by Week 20 will be discontinued from treatment and referred for follow-up care. All subjects (remitters and non-remitters) will be assessed at 20 weeks.